When construction improvements such as repairs or extensions are to be performed after a pipe or the like is buried, the ground must be dug up. At this time, the identifying block placed above the pipe is moved or temporarily removed. After the construction is completed, the block is restored to the former position. In this case, according to the conventional marker, the block is often placed at a wrong position, left behind, or lost. If the block is not placed at the correct position, a buried pipe or the like may be cut in another construction.